The present invention relates to a surface analyzer for analyzing a surface of material using a particle beam such as an electron microscope, an ion microanalyzer etc..
As disclosed in the official gazette of Japanese Patent Laid-Open No. 49-132976 (1974), a prior-art surface analyzer using a particle beam has been such that, in order to hermetically seal an opening by the use of a valve, through which the particle beam passes, a seal member is formed with front and rear slant surfaces in the shifting direction thereof, whereupon thrusts in the shifting direction are exerted on the slant surfaces from pins mounted on a stopping member and a shift member, so as to endow the seal member with a pressing force toward the opening.
In the prior art mentioned above, a frictional distance between the seal member and the seal surface of the opening becomes so long that the abrasion and seizure of the seal member such as a sealing 0-ring are produced. Especially in a scanning electron microscope for measuring the pattern line width of a semiconductor wafer, abraded powder which appears in a gate valve falls on the surface of the wafer to degrade the available percentage of the wafer. A further problem is that, in the microscope of this type requiring a high throughput, the gate valve seizes up in a short term to render the analysis impossible.